The invention relates to an image intensifier tube, comprising an envelope consisting of a jacket, a metal entrance window, and an exit window, said envelope accommodating an electron-optical system for imaging electrons, emerging from an entrance detection screen, on an exit screen.
An image intensifier tube of this kind is known, in the form of an X-ray image intensifier tube, from German Offenlegungsschrift No. 2513894 (Siemens, Sept. 30, 1976). The tube described therein is susceptible, notably during mounting activities, to, for example, damage caused by tools to be used and by jolting of the tube against hard objects, so that the tube is liable to implode in unfavorable circumstances. This risk is higher as the diameter of the entrance screen of the tube, and hence the volume of the tube, is made larger. A heavier construction of the entrance screen results in a lower quantum detection efficiency, and hence in a loss of sensitivity and a less favorable signal-to-noise ratio. A heavier construction of the jacket of the tube readily results in a very heavy tube which is difficult to handle.